staging: add zsmalloc to Kconfig/Makefile

Adds the new zsmalloc library to the staging Kconfig and Makefile

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Amperific <amperific@gmail.com>